1. Field of the Invention
The present invention relates to a slit valve with safety detect device to prevent clipping. More particularly, it relates to a safety detect device including a plurality of sensor to detect whether there are anything in the route that the seal plate moving.
2. Background of the Invention
There are many slit valves established between the plurality of different reaction chambers. The slit valves are used to act as the doors for the waiting processing wafer or processed wafer in/out the different chamber. The position of the slit valves in the prior art shown in FIG. 1. There includes a transfer chamber 1 used to transfer the wafer from one chamber to another chamber. A load-lock chamber 3 placed beside the transfer chamber 1 to load the wafer and lock. There also includes a processing chamber 2 posited beside the other side of the transfer chamber 1. The process chamber 2 is used to deal with the wafer, for example, etching, iron implanting or depositing the wafer. In FIG. 1, there are two slit valves 13, one is posited between the transfer chamber 1 and the load lock chamber 3, the other slit valves is posited between the transfer chamber 1 and the process chamber 2.
The conventional slit valves can not detect that there are something between the range of the seal plate moving, because there is not any safety sensor with the conventional slit valves. If there is a wafer or robot blade in the range of the seal plate moving, the wafer or robot will be clamped and damaged. There are many wafer damaged cases by the slit valves in many semiconductor companies. FIG. 2 shows the prior art of the slit valve comprising a clean dry air 30 used to push a seal plate 35 of a slit valve 25. The seal plate 35 is sealed up with a slit 20. The slit 20 is placed in the edge 10 of the transfer chamber and the edges 20a, 20b of the slit 20 is an inclined plane as shown in FIG. 2. The seal plate 35 is in the top of the slit valve 25 and sealed up with a slit 20, so the interval between the transfer chamber 1 and the processing chamber 2 can be sealed up.
FIG. 2 shows the wafer 40 is placed on a robot blade 45 and be transferred into a chamber through the slit 20. When the wafer 40 is on the way into the slit 20 and the slit valve 25 wants to seal up with the slit 20, then the wafer 40 will be clamped and damaged by the seal plate 35 of the slit valve 25. The technique shown in FIG. 2 exposes that there is not any safety detector on the slit valve or slit, that's why the wafer 40 always be damaged by the seal plate 35. This kind of the wafer damaged cases are too numerous to be counted in several semiconductor companies. It should adds the safety sensor on the slit valve to avoid the damage.